The present invention relates to a selective growth method, and to a semiconductor light emitting device and a fabrication method thereof, to each of which the selective growth method is applied.
GaN based compound semiconductors have become a focus of attention as semiconductor materials for semiconductor light emitting devices, and a variety of device designs and trials have been made to improve characteristics of semiconductor light emitting devices using GaN based compound semiconductors.
The GaN based semiconductor light emitting device emits light having a wavelength in a short-wavelength region, and therefore, it allows emission of light of blue or green. Accordingly, a full-color image display unit can be fabricated, for example, by combining the GaN based semiconductor light emitting devices with GaAs based semiconductor light emitting devices allowing emission of light of red.
The above-described GaN based semiconductor light emitting device can be fabricated by forming a mask having an opening on a sapphire substrate, forming a nitride layer by selective growth from the opening, and sequentially forming a cladding layer, a guide layer, and an active layer on a tilt growth plane of the nitride layer by selective growth. Such a light emitting device is excellent in luminous efficiency.
In the step of selective growth of the active layer in the above-described fabrication method, it is required to grow the active layer at a low temperature, and such growth of the active layer causes a problem that the growth rate is reduced with an increase in thickness of the active layer, and the repeatability of fabrication is also degraded. For example, in the case of forming an active layer of a multi-layer structure having multiple quantum wells, there occurs a phenomenon that the growth rate of the active layer becomes gradually low and thereby the thickness of the quantum well becomes gradually thin. In a light emitting device including an active layer of the multi-quantum well structure, to ensure excellent light emission characteristics, it is preferred that the thickness of one of the multiple quantum wells is equal to that of another of the multiple quantum wells. If the thickness of the quantum well becomes gradually thin, characteristics of the device are degraded, and more specifically, a half-value width of an emission wavelength peak becomes large, and the repeatability of fabrication is also degraded.